The study was published in the International Journal of Epidemiology on February 26. Researchers identified a 77 per cent increase of ear ailment symptoms such as earaches for sea swimmers versus non-swimmers. The risk for gastrointestinal symptoms like diarrhea and stomach aches went up by 29 per cent.

Researchers examined 19 studies from the U.K., U.S., Australia, Spain, Greece, and Mexico that linked swimming in the sea with illness, according to the study.

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"In high-income countries like the U.K., there is a perception that there is little risk to health of spending time in the sea," Dr. Anne Leonard, co-author of the study, said, according to BBC News. "Spending time in the sea does increase the probability of developing illnesses, such as ear ailments and problems involving the digestive system," she continued.

Given the wealth of the U.K, Dr. Leonard noted the water pollution could also occur in some of the richest countries in the world, according to BBC News.

But, there is some hope. As noted by research supervisor Dr. Will Gaze, most people can recover from illnesses without medical attention. But, seniors and young children, as well as those with pre-existing health conditions, are more vulnerable. The World Health Organization noted that as people grow older, their risk of disease and disability increases. They identified risk factors such as injury, poverty, elder maltreatment, development of noncommunicable diseases, and more, as targets for improvement in senior health.

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Young children are also vulnerable to these illnesses because they have yet to establish defenses against them, according to Caring For Kids. The website, published by the Canadian Paediatric Society, reported that in young children, most infections will not last very long. For cases of earaches, the website suggested a visit to the doctor and the possible need of antibiotics.

Swimming is a great workout because you use your body as a form of resistance against the water, Sport Ottawa wrote on their website. The activity can tone muscles, provide good low-impact therapy, help strengthen cardiovascular fitness, and more, they said.

Still, it's good to be aware of potential risks as the weather begins to heat up and more people take to the seas.

"We have come a long way in terms of cleaning up our waters, but our evidence shows there is still work to be done. We hope this research will contribute to further efforts to clean up our coastal waters," Dr. Gaze said.